1. Field of the Invention
The present invention generally relates to a magnetic head apparatus and, more particularly, to a magnetic head apparatus having a magnetic head which is supported by a support arm and contacts a recording medium.
2. Description of the Related Art
A magneto-optical disc apparatus has become popular as a disc apparatus which is capable of performing both recording and reproducing operations. The magneto-optical disc performs a high-density recording of information by using a laser beam and a disc provided with a magnetic thin-film thereon.
The magneto-optical disc apparatus projects a high-intensity laser beam to a surface of a magneto-optical disc (hereinafter referred to as a disc), when a recording operation is performed, so as to raise the temperature of the magnetic thin-film beyond a curie point or a temperature compensation point. A vertical magnetic field is applied from the opposite surface of the disc to reverse the direction of magnetization of the magnetic thin-film so as to record binary information on the disc. When a reproducing operation is performed, a laser beam, which does not affect the direction of magnetization of the magnetic thin-film, is projected on the disc so as to detect a rotational direction of a reflected laser beam from the disc. That is, the recorded binary information is reproduced by utilizing changes in the rotational direction of the reflected laser beam according to the direction of magnetization of the magnetic thin-film.
Such a magneto-optical disc apparatus is required to be a small size with a minimum thickness.
FIGS. 1A and 1B show a conventional magnetic head apparatus 21 provided in a magneto-optical disc apparatus. FIG. 1A is a plan view of the magnetic head apparatus 21, and FIG. 1B is a side view of the magnetic head apparatus 21.
The conventional magnetic head apparatus 21 comprises a magnetic head 22 which provides a recording magnetic field to a disc, a support arm 23 supporting the magnetic head 22, an operational unit 24 moving the magnetic head 22 up and down and a flexible print wiring board 25 electrically connecting the magnetic head 22 to an external device.
The magnetic head 22 includes a slider sliding on a surface of the disc. An E-shaped core and a coil are provided inside the slider. The coil is wound on a coil bobbin which is mounted on the core.
The support arm 23 is formed of a leaf spring material. A support portion 23a is formed on an extreme end of the support arm 23 to support the magnetic head 22. The opposite end of the support arm 23 is mounted to the operational unit 24 by welding and the like so that the magnetic head 22 is in contact with the disc.
The operational unit 24 is a rigid member to which the support arm 23 is mounted on an end portion thereof. The operational unit 24 is fixed, by means of screws, to a magnetic head apparatus mounting unit (not shown in the figures) which is movable in directions indicated by arrows A in FIG. 1B. A limiting portion 24a is integrally formed with the operational unit 24 at the end portion thereof so as to limit movement of the magnetic head 22 in a direction (indicated by an arrow B.sub.1 in FIG. 1B) opposite to the direction toward the disc.
The limiting portion 24a extends to a position where the magnetic head 22 is mounted. The limiting portion 24a contacts an upper surface of the magnetic head 22 so as to limit the moving position of the magnetic head 22 when a shock is applied to the magnetic head apparatus so that the magnetic head 22 is prevented from moving upwardly (in the direction indicated by the arrow B.sub.1) beyond the limiting portion 24a.
FIGS. 2A and 2B are views for explaining an operation of the conventional magnetic head apparatus 21. FIG. 2A shows a head-down state where the magnetic head 22 contacts a protective film of the disc. FIG. 2B shows a head-up state where the magnetic head 22 is lifted for loading or unloading the disc.
In the head-down state, the operational unit 24 is moved in a direction indicated by an arrow B.sub.2 of FIG. 2A by an operational lever 26 being moved downwardly. Thus, magnetic head 22 is pressed against the disc D by an elastic deformation force of the support arm 23.
In the head-up state, the operational lever 26 is moved upwardly in a direction indicated by an arrow B1 of FIG. 2B so that the magnetic head 22 is spaced away from the disc D. In the head-up state, since the support arm 23 is in a neutral position where the support arm 23 is not elastically deformed, the magnetic head 22 may swing up and down due to shocks applied to the magnetic head apparatus 21. In order to reduce the thickness of the entire apparatus provided with the magnetic head apparatus 21, a space above the magnetic head apparatus 21 must be minimized.
Accordingly, the magnetic head 22 contacts the limiting portion 24a, which is provided in a position where the upward movement of the magnetic head 22 is limited, so that the magnetic head 22 does not move upwardly beyond a predetermined height when it swings. That is, the limiting portion 24a limits a jumping action of the magnetic head 22.
In the apparatus provided with the conventional magnetic head apparatus 21, other component parts are provided above a height L.sub.1 shown in FIG. 2B. The height L.sub.1 is determined by adding a distance, which considers a terminal T protruding upwardly from the limiting portion 24a, to a height L.sub.0 which is a distance from the surface of the disc D to the uppermost end of the limit portion 24a. The terminal T is provided for electrically connecting the magnetic head 22 to the flexible print wiring board 25.
As mentioned above, in the conventional magnetic head apparatus, the limit portion 24a is provided to the operational unit 24, and the limit portion 24a contacts the upper surface of the magnetic head 22 so as to limit the upward jumping movement of the magnetic head 22 beyond the operational unit 24. Thus, the operational unit 24 extends to a position above the magnetic head 22, and the height (thickness) of the magnetic head apparatus 21 is defined by the limit portion 24a of the operational unit 24. Accordingly, the presence of the limit portion 24a is an obstacle to reduction of the height of the magnetic head apparatus 21.
Additionally, in the magnetic head apparatus 21, since the magnetic head 22 is supported at a single point on the end portion of the support arm 23, the end portion of the support arm 23 is elastically bent due to the weight of the magnetic head 22. The magnetic head 22 is inclined in a direction indicated by an arrow A.sub.1 in FIG. 2B so that the rear end of the magnetic head is lowered than the front end of the magnetic head 22. Thus, a leading end of the disc D being inserted in a direction indicated by an arrow C does not engage with the front end of the magnetic head 22, resulting in a smooth insertion of the disc D. The position of the rear end of the magnetic head 22 is determined by the flexible print wiring board 25 which is connected to the magnetic head 22 so that the magnetic head 22 is maintained at an angle .theta..sub.2.
As mentioned above, in the conventional magnetic head apparatus 21, the rear end of the magnetic head 22 is connected to the flexible print wiring board 25 so as to limit the downward movement of the magnetic head 22, the angle .theta..sub.2 of the magnetic head 22 is determined by arrangement of the flexible print wiring board 25. Thus, the lowermost end of the magnetic head cannot be well defined. Accordingly, a distance (height) H.sub.2 between the surface of the disc D and the rear end of the magnetic head 22 must include a tolerance, resulting in an obstacle to the reduction of the height (thickness) of the magnetic head apparatus 21.
Referring now to FIG. 1A, the conventional support arm 23 is formed to be an easily and elastically deformable structure by forming an opening 23b in a flat leaf spring member which substantially reduces the width of the leaf spring member. That is, the support arm 23 is elastically deformed at a portion provided with the opening 23b.
As mentioned above, in the head-up state, the operational lever 26 is moved upwardly to move the magnetic head 22 upwardly in the direction indicated by the arrow B.sub.1. In this state, the support arm 23 is held only by the operational unit 24 and, thus, the support arm 23 is easily and elastically bendable in the directions indicated by arrows B.sub.1 and B.sub.2. Thus, the distance H.sub.2 between the surface of the disc D and the magnetic head 22 is provided with a sufficient tolerance to absorb the swinging motion of the magnetic head 22 due to vibration when the disc D is inserted in the direction indicated by the arrow C.
Since the support arm 23 is formed from a leaf spring material, the support arm 23 is bendable in portions other than the portion provided with the opening 23b. Thus, the tolerance provided to the height H.sub.2 is further increased to absorb the amount of deformation due to shocks and vibration. Thus, the space defined by the height H.sub.2 is an obstacle to the reduction of the height of the magnetic head apparatus 21.
FIG. 3 is a perspective view of a connecting portion between the magnetic head 22 and the flexible print wiring board 25.
The connection between the magnetic head 22 and the flexible print wiring board 25 is performed by soldering connection pins 22b protruding from the coil bobbin 22a of the magnetic head 22 to the land portions 25a provided in the flexible print wiring board 25. First, ends of the coil wire wound on the coil bobbin 22a are engaged with the respective connection pins 22b. Thereafter, openings (not shown in the figure) formed in the land portions of the flexible print wiring board 25 are fit to the respective connection pins 22b. Then the land portions and connection pins 22b are soldered. Thus, the connection pins 22b protrude upwardly from the magnetic head 22.
FIG. 4 shows, similar to FIG. 2B, a head-up state where the magnetic head 22 is separated from the disc for loading and unloading the disc.
In the head-up state shown in FIG. 4, as mentioned above, the support arm 23 is limited by the limiting portion 24a provided to the operational unit 24. That is, when the magnetic head 22 is moved upwardly and the magnetic head 22 contacts the limiting portion 24a, further upward movement of the magnetic head 22 is limited by the limiting portion 24a. In this state, the connection pins protrude in a direction indicated by an arrow B.sub.1, the connection pins protrude upwardly (in the direction indicated by the arrow B.sub.1) beyond the limiting portion 24a. Accordingly, in order to prevent the pins 22 colliding with other component parts provided above the magnetic head apparatus 21, a predetermined distance d.sub.1 must be provided between the limiting portion 24a and other component parts provided above the magnetic head apparatus 21.
That is, in the conventional magnetic head apparatus 21, since the connection pins 22b protruding from the magnetic head 22 protrude beyond the limiting portion 24a when the magnetic head 22 jumps up, a space is required to avoid a collision of the connection pins 22b with the limiting portion 22b. This space may be an obstacle to the reduction of the height of the magnetic head apparatus 21.
In the magnetic head apparatus 21, since the flexible print wiring board 25 is placed on the support arm 23, bending of the flexible print wiring board 25 must be taken into consideration.
FIG. 5A is an illustration of a portion of the structure of support arm 23 and the flexible print wiring board 25 in the head-up state; FIG. 5B is an illustration of the portion of the structure shown in FIG. 5A in the head-down state.
In the head-up state, the flexible print wiring board 25 is arranged on the surface of the support arm 23 without space therebetween. However, in the head-down state, the support arm 23 is bent in a direction indicated by an arrow B.sub.1 as shown in FIG. 5B, and a length of the wiring path of the flexible print wiring board 25 is shortened. Thus, a bend is generated in the flexible print wiring board 25 in the upward direction (direction indicated by an arrow F in FIG. 5B). Thus, in the magnetic head apparatus 21, a space is provided above the support arm 23 so that the bend portion of the flexible print wiring board 25 does not contact other component parts provided above the magnetic head apparatus 21.
As mentioned above, in the conventional magnetic head apparatus 21, a space must be provided above the support arm 23 so as to avoid interference of the bent portion of the flexible print wiring board with other component parts. Thus, the space is an obstacle to the reduction of the height of the conventional magnetic head apparatus 21.